Juvenile idiopathic arthritis (JIA) is defined by the International League of Associations for Rheumatology (ILAR) as arthritis of unknown aetiology beginning before the sixteenth birthday and persisting for at least six weeks with other known conditions excluded 1. JIA is one of the common chronic diseases of childhood with a prevalence of approximately 1 in 1000 in the West 2. JIA often persists into adulthood and can result in significant long-term morbidity, including physical disability 3. Recent major advances in treatment have greatly improved short and medium term outcome for children with JIA 4. In this article I will discuss classification, clinical presentation, differential diagnosis and recommended treatment of JIA.